1 files changed, 259 insertions, 113 deletions

diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
index bc5788000018..6a897788f5a7 100755
--- a/scripts/leaking_addresses.pl
+++ b/scripts/leaking_addresses.pl
@@ -3,15 +3,20 @@
 # (c) 2017 Tobin C. Harding <me@tobin.cc>
 # Licensed under the terms of the GNU GPL License version 2
 #
-# leaking_addresses.pl: Scan 64 bit kernel for potential leaking addresses.
+# leaking_addresses.pl: Scan the kernel for potential leaking addresses.
 #  - Scans dmesg output.
 #  - Walks directory tree and parses each file (for each directory in @DIRS).
 #
 # Use --debug to output path before parsing, this is useful to find files that
 # cause the script to choke.
+
 #
-# You may like to set kptr_restrict=2 before running script
-# (see Documentation/sysctl/kernel.txt).
+# When the system is idle it is likely that most files under /proc/PID will be
+# identical for various processes.  Scanning _all_ the PIDs under /proc is
+# unnecessary and implies that we are thoroughly scanning /proc.  This is _not_
+# the case because there may be ways userspace can trigger creation of /proc
+# files that leak addresses but were not present during a scan.  For these two
+# reasons we exclude all PID directories under /proc except '1/'
 
 use warnings;
 use strict;
@@ -22,9 +27,10 @@ use Cwd 'abs_path';
 use Term::ANSIColor qw(:constants);
 use Getopt::Long qw(:config no_auto_abbrev);
 use Config;
+use bigint qw/hex/;
+use feature 'state';
 
 my $P = $0;
-my $V = '0.01';
 
 # Directories to scan.
 my @DIRS = ('/proc', '/sys');
@@ -32,10 +38,9 @@ my @DIRS = ('/proc', '/sys');
 # Timer for parsing each file, in seconds.
 my $TIMEOUT = 10;
 
-# Script can only grep for kernel addresses on the following architectures. If
-# your architecture is not listed here and has a grep'able kernel address please
-# consider submitting a patch.
-my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64');
+# Kernel addresses vary by architecture.  We can only auto-detect the following
+# architectures (using `uname -m`).  (flag --32-bit overrides auto-detection.)
+my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64', 'x86');
 
 # Command line options.
 my $help = 0;
@@ -43,46 +48,34 @@ my $debug = 0;
 my $raw = 0;
 my $output_raw = "";    # Write raw results to file.
 my $input_raw = "";     # Read raw results from file instead of scanning.
-
 my $suppress_dmesg = 0;         # Don't show dmesg in output.
 my $squash_by_path = 0;         # Summary report grouped by absolute path.
 my $squash_by_filename = 0;     # Summary report grouped by filename.
-
-# Do not parse these files (absolute path).
-my @skip_parse_files_abs = ('/proc/kmsg',
-                            '/proc/kcore',
-                            '/proc/fs/ext4/sdb1/mb_groups',
-                            '/proc/1/fd/3',
-                            '/sys/firmware/devicetree',
-                            '/proc/device-tree',
-                            '/sys/kernel/debug/tracing/trace_pipe',
-                            '/sys/kernel/security/apparmor/revision');
-
-# Do not parse these files under any subdirectory.
-my @skip_parse_files_any = ('0',
-                            '1',
-                            '2',
-                            'pagemap',
-                            'events',
-                            'access',
-                            'registers',
-                            'snapshot_raw',
-                            'trace_pipe_raw',
-                            'ptmx',
-                            'trace_pipe');
-
-# Do not walk these directories (absolute path).
-my @skip_walk_dirs_abs = ();
-
-# Do not walk these directories under any subdirectory.
-my @skip_walk_dirs_any = ('self',
-                          'thread-self',
-                          'cwd',
-                          'fd',
-                          'usbmon',
-                          'stderr',
-                          'stdin',
-                          'stdout');
+my $kernel_config_file = "";    # Kernel configuration file.
+my $opt_32bit = 0;              # Scan 32-bit kernel.
+my $page_offset_32bit = 0;      # Page offset for 32-bit kernel.
+
+# Skip these absolute paths.
+my @skip_abs = (
+        '/proc/kmsg',
+        '/proc/device-tree',
+        '/proc/1/syscall',
+        '/sys/firmware/devicetree',
+        '/sys/kernel/debug/tracing/trace_pipe',
+        '/sys/kernel/security/apparmor/revision');
+
+# Skip these under any subdirectory.
+my @skip_any = (
+        'pagemap',
+        'events',
+        'access',
+        'registers',
+        'snapshot_raw',
+        'trace_pipe_raw',
+        'ptmx',
+        'trace_pipe',
+        'fd',
+        'usbmon');
 
 sub help
 {
@@ -91,31 +84,22 @@ sub help
         print << "EOM";
 
 Usage: $P [OPTIONS]
-Version: $V
 
 Options:
 
-        -o, --output-raw=<file>  Save results for future processing.
-        -i, --input-raw=<file>   Read results from file instead of scanning.
-            --raw                Show raw results (default).
-            --suppress-dmesg     Do not show dmesg results.
-            --squash-by-path     Show one result per unique path.
-            --squash-by-filename Show one result per unique filename.
-        -d, --debug              Display debugging output.
-        -h, --help, --version    Display this help and exit.
-
-Examples:
-
-        # Scan kernel and dump raw results.
-        $0
-
-        # Scan kernel and save results to file.
-        $0 --output-raw scan.out
+        -o, --output-raw=<file>         Save results for future processing.
+        -i, --input-raw=<file>          Read results from file instead of scanning.
+              --raw                     Show raw results (default).
+              --suppress-dmesg          Do not show dmesg results.
+              --squash-by-path          Show one result per unique path.
+              --squash-by-filename      Show one result per unique filename.
+        --kernel-config-file=<file>     Kernel configuration file (e.g /boot/config)
+        --32-bit                        Scan 32-bit kernel.
+        --page-offset-32-bit=o          Page offset (for 32-bit kernel 0xABCD1234).
+        -d, --debug                     Display debugging output.
+        -h, --help, --version           Display this help and exit.
 
-        # View summary report.
-        $0 --input-raw scan.out --squash-by-filename
-
-Scans the running (64 bit) kernel for potential leaking addresses.
+Scans the running kernel for potential leaking addresses.
 
 EOM
         exit($exitcode);
@@ -131,6 +115,9 @@ GetOptions(
         'squash-by-path'        => \$squash_by_path,
         'squash-by-filename'    => \$squash_by_filename,
         'raw'                   => \$raw,
+        'kernel-config-file=s'  => \$kernel_config_file,
+        '32-bit'                => \$opt_32bit,
+        'page-offset-32-bit=o'  => \$page_offset_32bit,
 ) or help(1);
 
 help(0) if ($help);
@@ -146,16 +133,19 @@ if (!$input_raw and ($squash_by_path or $squash_by_filename)) {
         exit(128);
 }
 
-if (!is_supported_architecture()) {
+if (!(is_supported_architecture() or $opt_32bit or $page_offset_32bit)) {
         printf "\nScript does not support your architecture, sorry.\n";
         printf "\nCurrently we support: \n\n";
         foreach(@SUPPORTED_ARCHITECTURES) {
                 printf "\t%s\n", $_;
         }
+        printf("\n");
+
+        printf("If you are running a 32-bit architecture you may use:\n");
+        printf("\n\t--32-bit or --page-offset-32-bit=<page offset>\n\n");
 
-        my $archname = $Config{archname};
-        printf "\n\$ perl -MConfig -e \'print \"\$Config{archname}\\n\"\'\n";
-        printf "%s\n", $archname;
+        my $archname = `uname -m`;
+        printf("Machine hardware name (`uname -m`): %s\n", $archname);
 
         exit(129);
 }
@@ -177,49 +167,183 @@ sub dprint
 
 sub is_supported_architecture
 {
-        return (is_x86_64() or is_ppc64());
+        return (is_x86_64() or is_ppc64() or is_ix86_32());
 }
 
-sub is_x86_64
+sub is_32bit
 {
-        my $archname = $Config{archname};
-
-        if ($archname =~ m/x86_64/) {
+        # Allow --32-bit or --page-offset-32-bit to override
+        if ($opt_32bit or $page_offset_32bit) {
                 return 1;
         }
-        return 0;
+
+        return is_ix86_32();
+}
+
+sub is_ix86_32
+{
+       state $arch = `uname -m`;
+
+       chomp $arch;
+       if ($arch =~ m/i[3456]86/) {
+               return 1;
+       }
+       return 0;
+}
+
+sub is_arch
+{
+       my ($desc) = @_;
+       my $arch = `uname -m`;
+
+       chomp $arch;
+       if ($arch eq $desc) {
+               return 1;
+       }
+       return 0;
+}
+
+sub is_x86_64
+{
+        state $is = is_arch('x86_64');
+        return $is;
 }
 
 sub is_ppc64
 {
-        my $archname = $Config{archname};
+        state $is = is_arch('ppc64');
+        return $is;
+}
 
-        if ($archname =~ m/powerpc/ and $archname =~ m/64/) {
-                return 1;
+# Gets config option value from kernel config file.
+# Returns "" on error or if config option not found.
+sub get_kernel_config_option
+{
+        my ($option) = @_;
+        my $value = "";
+        my $tmp_file = "";
+        my @config_files;
+
+        # Allow --kernel-config-file to override.
+        if ($kernel_config_file ne "") {
+                @config_files = ($kernel_config_file);
+        } elsif (-R "/proc/config.gz") {
+                my $tmp_file = "/tmp/tmpkconf";
+
+                if (system("gunzip < /proc/config.gz > $tmp_file")) {
+                        dprint "$0: system(gunzip < /proc/config.gz) failed\n";
+                        return "";
+                } else {
+                        @config_files = ($tmp_file);
+                }
+        } else {
+                my $file = '/boot/config-' . `uname -r`;
+                chomp $file;
+                @config_files = ($file, '/boot/config');
         }
-        return 0;
+
+        foreach my $file (@config_files) {
+                dprint("parsing config file: %s\n", $file);
+                $value = option_from_file($option, $file);
+                if ($value ne "") {
+                        last;
+                }
+        }
+
+        if ($tmp_file ne "") {
+                system("rm -f $tmp_file");
+        }
+
+        return $value;
+}
+
+# Parses $file and returns kernel configuration option value.
+sub option_from_file
+{
+        my ($option, $file) = @_;
+        my $str = "";
+        my $val = "";
+
+        open(my $fh, "<", $file) or return "";
+        while (my $line = <$fh> ) {
+                if ($line =~ /^$option/) {
+                        ($str, $val) = split /=/, $line;
+                        chomp $val;
+                        last;
+                }
+        }
+
+        close $fh;
+        return $val;
 }
 
 sub is_false_positive
 {
         my ($match) = @_;
 
+        if (is_32bit()) {
+                return is_false_positive_32bit($match);
+        }
+
+        # 64 bit false positives.
+
         if ($match =~ '\b(0x)?(f|F){16}\b' or
             $match =~ '\b(0x)?0{16}\b') {
                 return 1;
         }
 
-        if (is_x86_64) {
-                # vsyscall memory region, we should probably check against a range here.
-                if ($match =~ '\bf{10}600000\b' or
-                    $match =~ '\bf{10}601000\b') {
-                        return 1;
-                }
+        if (is_x86_64() and is_in_vsyscall_memory_region($match)) {
+                return 1;
         }
 
         return 0;
 }
 
+sub is_false_positive_32bit
+{
+       my ($match) = @_;
+       state $page_offset = get_page_offset();
+
+       if ($match =~ '\b(0x)?(f|F){8}\b') {
+               return 1;
+       }
+
+       if (hex($match) < $page_offset) {
+               return 1;
+       }
+
+       return 0;
+}
+
+# returns integer value
+sub get_page_offset
+{
+       my $page_offset;
+       my $default_offset = 0xc0000000;
+
+       # Allow --page-offset-32bit to override.
+       if ($page_offset_32bit != 0) {
+               return $page_offset_32bit;
+       }
+
+       $page_offset = get_kernel_config_option('CONFIG_PAGE_OFFSET');
+       if (!$page_offset) {
+               return $default_offset;
+       }
+       return $page_offset;
+}
+
+sub is_in_vsyscall_memory_region
+{
+        my ($match) = @_;
+
+        my $hex = hex($match);
+        my $region_min = hex("0xffffffffff600000");
+        my $region_max = hex("0xffffffffff601000");
+
+        return ($hex >= $region_min and $hex <= $region_max);
+}
+
 # True if argument potentially contains a kernel address.
 sub may_leak_address
 {
@@ -238,14 +362,8 @@ sub may_leak_address
                 return 0;
         }
 
-        # One of these is guaranteed to be true.
-        if (is_x86_64()) {
-                $address_re = '\b(0x)?ffff[[:xdigit:]]{12}\b';
-        } elsif (is_ppc64()) {
-                $address_re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
-        }
-
-        while (/($address_re)/g) {
+        $address_re = get_address_re();
+        while ($line =~ /($address_re)/g) {
                 if (!is_false_positive($1)) {
                         return 1;
                 }
@@ -254,6 +372,31 @@ sub may_leak_address
         return 0;
 }
 
+sub get_address_re
+{
+        if (is_ppc64()) {
+                return '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
+        } elsif (is_32bit()) {
+                return '\b(0x)?[[:xdigit:]]{8}\b';
+        }
+
+        return get_x86_64_re();
+}
+
+sub get_x86_64_re
+{
+        # We handle page table levels but only if explicitly configured using
+        # CONFIG_PGTABLE_LEVELS.  If config file parsing fails or config option
+        # is not found we default to using address regular expression suitable
+        # for 4 page table levels.
+        state $ptl = get_kernel_config_option('CONFIG_PGTABLE_LEVELS');
+
+        if ($ptl == 5) {
+                return '\b(0x)?ff[[:xdigit:]]{14}\b';
+        }
+        return '\b(0x)?ffff[[:xdigit:]]{12}\b';
+}
+
 sub parse_dmesg
 {
         open my $cmd, '-|', 'dmesg';
@@ -268,26 +411,20 @@ sub parse_dmesg
 # True if we should skip this path.
 sub skip
 {
-        my ($path, $paths_abs, $paths_any) = @_;
+        my ($path) = @_;
 
-        foreach (@$paths_abs) {
+        foreach (@skip_abs) {
                 return 1 if (/^$path$/);
         }
 
         my($filename, $dirs, $suffix) = fileparse($path);
-        foreach (@$paths_any) {
+        foreach (@skip_any) {
                 return 1 if (/^$filename$/);
         }
 
         return 0;
 }
 
-sub skip_parse
-{
-        my ($path) = @_;
-        return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any);
-}
-
 sub timed_parse_file
 {
         my ($file) = @_;
@@ -313,11 +450,9 @@ sub parse_file
                 return;
         }
 
-        if (skip_parse($file)) {
-                dprint "skipping file: $file\n";
+        if (! -T $file) {
                 return;
         }
-        dprint "parsing: $file\n";
 
         open my $fh, "<", $file or return;
         while ( <$fh> ) {
@@ -328,12 +463,14 @@ sub parse_file
         close $fh;
 }
 
-
-# True if we should skip walking this directory.
-sub skip_walk
+# Checks if the actual path name is leaking a kernel address.
+sub check_path_for_leaks
 {
         my ($path) = @_;
-        return skip($path, \@skip_walk_dirs_abs, \@skip_walk_dirs_any)
+
+        if (may_leak_address($path)) {
+                printf("Path name may contain address: $path\n");
+        }
 }
 
 # Recursively walk directory tree.
@@ -342,7 +479,6 @@ sub walk
         my @dirs = @_;
 
         while (my $pwd = shift @dirs) {
-                next if (skip_walk($pwd));
                 next if (!opendir(DIR, $pwd));
                 my @files = readdir(DIR);
                 closedir(DIR);
@@ -353,11 +489,21 @@ sub walk
                         my $path = "$pwd/$file";
                         next if (-l $path);
 
+                        # skip /proc/PID except /proc/1
+                        next if (($path =~ /^\/proc\/[0-9]+$/) &&
+                                 ($path !~ /^\/proc\/1$/));
+
+                        next if (skip($path));
+
+                        check_path_for_leaks($path);
+
                         if (-d $path) {
                                 push @dirs, $path;
-                        } else {
-                                timed_parse_file($path);
+                                next;
                         }
+
+                        dprint "parsing: $path\n";
+                        timed_parse_file($path);
                 }
         }
 }